As far as i know sacrifice is only way to restock your army without traveling between islands. I usually wait for 3-4 lvl worth of leadership and pick some easy fight, before finishing spend 5-6 turns sacrificing/resurrecting units.
Why would you want astral resistance ? You need to kill as much as possible to gain enough HP worth for new units.
For shamans i think your mistaken. They can get magic axes almost every turn thx to thirst for glory, and fighting spirit. Lets say you use magic axes to kill some enemy spent 8 adrenaline, then with other orc units kill and every orc get 4-12 more adrenaline (shaman even more because thirst for glory), it`s good chance that shamans will regain magic axes in next turn. Use them to heal any dmg made to your units for 8 adrenaline, and again next turn if some unit is killed by your orc units shamans get 4-12+ more adrenaline get over max and reset magic axes again . . . and so on, almost every turn magic axes available. If it doesnt happen cast some totem to force enemy to waste turn killing it, and save your melee units in enemy lines.
About Mage/Shrek team my bad, i somewhere read about double casting with Shrek team and made mistake here.
For spirit strike i think your wrong, since i just tried it. 27 chieftains inflict 1500-2000 dmg with spirit strike to swordsman, then i added 200 blood shamans in army, and they inflict 7000-8500 dmg. Still think it`s crappy?
Every blood shaman give 1 astral dmg to spirit strike ability to chieftains, so around 100+ shamans it get quiet a punch (spirit STRIKE-punch
get it ? ).
And ogre`s and chieftains dont give each other morale. but here i must say i would pick chieftains : ogre arent affected with Orc`s ear item (-10% leadership so ogre 1000, chieftains 1080), ogre 680 hp - chieftains 850 and higher resistances, ogre dmg 50-60 - chieftains 65-91 that`s 50% more, drain is imba ability - sneer much weaker, but chieftains have aoe spirit strike. So in my opinion chieftain is better.
But as for me i cant use neither since i still cant find error with onslaught skill and adrenaline distribution to orcs in 1 round of battle. I tried to use Toadstool item to give my orcs 5-7 adrenaline in first round and it`s not working either
Try to figure this out : i have shamans, ogre, chieftan, veteran orc, and blood shaman on start of battle no adrenaline for my army. Dismiss ogres and take catapults and on start of battle all my units have 5-10 adrenaline !!! WTF is wrong with that skill ?